U.S. patent application number 10/493020 was filed with the patent office on 2004-12-09 for continuously variable transmission with axially movable pulley hub units.
Invention is credited to Kapaan, Hendrikus Jan, Meaney, Paul Bernard, Van Leeuwen, Bernardus Gerardus, Vissers, Cornelius Petrus Antonius, Zwarts, Jacobus.
Application Number | 20040248678 10/493020 |
Document ID | / |
Family ID | 26643401 |
Filed Date | 2004-12-09 |
United States Patent
Application |
20040248678 |
Kind Code |
A1 |
Kapaan, Hendrikus Jan ; et
al. |
December 9, 2004 |
Continuously variable transmission with axially movable pulley hub
units
Abstract
A continuously variable transmission comprises a housing (1)
which accommodates two pulley sets (2, 3) and an endless flexible
drive element (24) fitted around said pulley sets for transferring
a torque, one of said pulley sets being provided with coupling
means (14) for an ingoing shaft and the other with coupling means
(22) for an outgoing shaft, said pulley sets each comprising two
discs (4, 5) enclosing a groove which increases in radially outward
direction, and screw drive means (6) for changing the distance
between the two discs of each pulley set with the aim of changing
the transmission ratio. Each disc is connected to a hub unit (7, 8)
comprising a rolling element bearing means (9, 10, 30) for
rotatably supporting the disc, each hub unit being axially
displaceably supported with respect to the housing.
Inventors: |
Kapaan, Hendrikus Jan; (DM
Nieuwegein, NL) ; Vissers, Cornelius Petrus Antonius;
(Den Dungen, NL) ; Zwarts, Jacobus; (Nieuwegein,
NL) ; Van Leeuwen, Bernardus Gerardus; (Nieuwegein,
NL) ; Meaney, Paul Bernard; (Utrecht, NL) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 19928
ALEXANDRIA
VA
22320
US
|
Family ID: |
26643401 |
Appl. No.: |
10/493020 |
Filed: |
April 19, 2004 |
PCT Filed: |
October 22, 2002 |
PCT NO: |
PCT/NL02/00667 |
Current U.S.
Class: |
474/8 ; 474/20;
474/41 |
Current CPC
Class: |
F16H 9/20 20130101; F16H
63/067 20130101 |
Class at
Publication: |
474/008 ;
474/020; 474/041 |
International
Class: |
F16H 055/56; F16H
009/12; F16H 061/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 22, 2001 |
NL |
1019204 |
Jun 2, 2002 |
NL |
1019910 |
Claims
1. Continuously variable transmission, comprising a housings which
accommodates two pulley sets and an endless flexible drive element
fitted around said pulley sets for transferring a torque, one of
said pulley sets being provided with coupling means for an ingoing
shaft and the other with coupling means for an outgoing shaft, said
pulley sets each comprising two discs enclosing a groove which
increases in radially outward direction, and screw drive means for
changing the distance between the two discs of each pulley set with
the aim of changing the transmission ratio, each disc being
connected to a hub unit comprising bearing means supporting the
disc rotatably with respect to the housing, characterized in that
said hub unit also comprised bearing means supporting the disc
axially displaceably with respect to the housing.
2. Transmission according to claim 1, wherein each hub unit is
supported with respect to the housing by means of a linear bearing
e.g. a plain bearing or a ball/raceway bearing.
3. Transmission according to claim 2, wherein each hub unit
comprises an outer ring or sleeve within which the rolling element
bearing means is fixed, and the housing comprises corresponding
cylinder parts in each of which a sleeve is slidably accommodated
through the plain bearing.
4. Transmission according to claim 1, wherein each hub unit
comprises a double row angular contact bearing.
5. Transmission according to claim 1, wherein at least one rolling
element bearing means comprises a 4-point angular contact ball
bearing.
6. Transmission unit according to claim 1, wherein at least one
rolling element bearing means comprises an asymmetric angular
contact bearing.
7. Transmission according to claim 1, wherein each bearing means
comprises a rolling element bearing having an inner ring and an
outer ring the raceways of which are in rolling contact with a
series of rolling elements said contacts between the rolling
elements e and at least one of the rings allowing axial
displacements.
8. Transmission according to claim 7, wherein the rings of at least
one rolling element bearing have a cylindrical raceway, and the
rolling elements have a cylindrical shape.
9. Transmission according to claim 7, wherein the rings of at least
one rolling element bearings have a crowned raceway, and the
rolling elements have a crowned shape.
10. Transmission according to claim 8, wherein one of the rings has
shoulders which enclose the cylindrical raceway, the rolling
elements being accommodated with slight play between the shoulders
the width of the raceway of the other ring being larger than the
distance between said shoulders.
11. Transmission according to claim 1, wherein each coupling means
comprises a telescoping member for engaging a corresponding
telescoping end of an ingoing shaft or an outgoing shaft.
12. Transmission according to claim 1, wherein the screw drive
means of each pulley set comprise a central screw shaft with
opposite screw thread parts each disc or hub unit being provided
with a nut which engages one of said screw thread parts.
13. Transmission according to claim 12, wherein each screw shaft is
connected to a mechanical control means and or
electrical/electronic control means.
14. Transmission according to claim 1, wherein the discs are each
slidably accommodated on a hollow central shaft.
15. Transmission according to claim 1, wherein at least one rolling
element bearing means comprises an asymmetric angular contact ball
bearing.
16. Transmission according to claim 1, wherein at least one screw
actuator is a roller screw actuator.
17. Transmission according to claim 1, wherein at least one screw
actuator is a ball screw actuator.
18. Transmission according to claim 1, wherein at least one screw
actuator is a friction screw actuator.
19. Transmission according to claim 1, wherein the nuts of the
screw actuators are accommodated on a common drive shaft extending
through the pulley sets.
20. Transmission according to claim 1, wherein the nuts are
provided with drive means, e.g. splines for connection to the drive
clutch, control unit and differential.
21. Transmission according to claim 13 wherein the control means
comprises an electrical, electronic, hydraulic device or a
combination of these.
22. Transmission according to claim 1, wherein a sensor is provided
for sensing a parameter associated with the rotational movement of
the drive shaft, load, temperature etc.
23. Transmission according to claim 1, wherein a sensor is provided
for sensing a parameter associated with the rotational movement of
the drive shaft and/or driven shaft.
24. Transmission according to claim 1, wherein the pulley sets are
mutually connected by splined bushing.
25. Transmission according to claim 1, wherein the flexible element
is a pull chain or push belt, e.g. a flexible metallic belt, non
metallic belt, composite belt or combination of these.
26. Transmission according to claim 1, wherein the flexible element
is a chain, belt (push or pull).
27. Transmission according to claim 1, wherein the discs of each
one pulley set are identical.
28. Transmission according to claim 1, wherein at least one of the
pulley sets comprises a sensor for sensing a parameter associated
with the rotational movement of the drive shaft, load, temperature
etc.
Description
[0001] The invention is related to a continuously variable
transmission, comprising a housing which accommodates two pulley
sets and an endless flexible element fitted around said pulley sets
for transferring a torque, one of said pulley sets being provided
with coupling means for an ingoing shaft and the other with
coupling means for an outgoing shaft, said pulley sets each
comprising two discs enclosing a groove which increases in radially
outward direction and screw drive means for changing the distance
between the two discs of each pulley set with the aim of changing
the transmission ratio.
[0002] Such a continuously variable transmission is generally
known. The pulley sets are accommodated on an ingoing shaft,
respectively an outgoing shaft, which shafts are rotatably
supported with respect to the housing through rolling element
bearings. Usually, one of the discs of each pulley set is slidable
with respect to the corresponding shaft through a key/groove
connection, or a ball/raceway connection.
[0003] The pulleys are therefore indirectly supported with respect
to the housing, that is through the shafts. The object of the
invention is to provide a continuously variable transmission in
which the support of the pulleys is improved and manufacturing
costs are reduced. This object is achieved in that each disc is
connected-to a hub unit comprising a rolling element bearing means
for supporting the disc rotatably as well as axially displaceably
with respect to the housing.
[0004] In the continuously variable transmission according to the
invention, the pulley sets are directly supported with respect to
the housing through their hubs. Said hubs in turn can be supported
with respect to the housing by means of a plain bearing or
ball/raceway or key/groove connection. Thus, the discs can freely
carry out axial movements upon changing the transmission ratio. The
pulley sets for the drive shaft and the driven shaft can have a
high degree of uniformity having regard to the fact that the discs
thereof move simultaneously from each other and towards each
other.
[0005] The hub units should be able to support the discs under
loading conditions in a stable fashion. To that end, each hub unit
may comprise a double row angular contact bearing. Preferably, each
hub unit comprises a sleeve or outer ring within which the rolling
element bearing means is fixed, and the housing comprises
corresponding cylinder parts in each of which a sleeve is slidably
accommodated through a sliding/axial moveable bearing.
[0006] According to a second embodiment, at least one bearing means
may comprise a rolling element bearing having an inner ring and an
outer ring the raceways of which are in rolling contact with a
series of rolling elements, said contacts between the rolling
elements and at least one of the rings allowing axial
displacements. The axial displacements of the bearing rings may be
obtained in several ways. According to a first possibility, the
rings of at least one rolling element bearing can have a
cylindrical raceway, and the rolling elements can have a
cylindrical shape. In that case, one of the rings of the rolling
element bearing may have shoulders which enclose the cylindrical
raceway, the rolling elements being accommodated with slight play
between the shoulders, the width of the raceway of the other ring
being larger than the distance between said shoulders. In view of
the moment loading on the discs of the pulley sets it may be
necessary to provide a special crowning or curvature on the rollers
and raceways; as an example, the so-called CARBS.RTM. bearing may
be applied.
[0007] A solid, simple layout is obtained in case each hub unit
comprises an inner ring member, which is integral with the
corresponding pulley.
[0008] With the aim of accommodating the axial movements of the
pulley hub units, each coupling means comprises a telescoping end
for engaging a corresponding telescoping end of an ingoing shaft or
an outgoing shaft.
[0009] The linear moving screw drive means of each pulley set
comprise a central screw shaft with opposite screw thread parts,
each disc or pulley hub unit being provided with a nut which
engages one of said screw thread parts. The nut of the ball screw
and the inner ring of the support bearing can be made of one
piece.
[0010] The invention will now be described further with reference
to several embodiments of the continuously variable transmission
shown in the drawings.
[0011] FIG. 1 shows a first embodiment of the continuously variable
transmission according to the invention.
[0012] FIG. 2 shows a second embodiment.
[0013] The continuously variable transmission shown in FIG. 1
comprises a housing 1 which accommodates two pulley sets 2, 3. The
pulley sets 2, 3 each contain two discs 4, 5 which enclose a
V-shaped groove. A belt or other endless flexible element 24 (push
or pull) is accommodated in the grooves between the discs 4, 5 of
the two pulley sets 2, 3.
[0014] The discs 4, 5 of the pulley sets 2, 3 can be moved towards
and from each other so as to change the transmission ratio between
the pulley sets 2, 3. The discs 4, 5 are to that end supported each
by respective pulley hub units 7, 8. These pulley hub units 7, 8
are axially displaceably supported with respect to the housing 1 by
means of e.g. plain bearings 10. These plain bearings each comprise
a sleeve 12 which slideably fits in the correspondingly shaped
cylinder part 13 of the housing 1.
[0015] Furthermore, the pulley hub units 7, 8 each comprise a
double row angular contact bearing 9, which are greased and sealed
for life. By means of this double row angular contact bearing 9,
the discs 4, 5 in question are rotatably supported with respect to
the housing 1 in a very stable fashion.
[0016] The double row angular contact bearings 9 each consists of a
common inner ring member 11 which is integral with the
corresponding disc 4, 5. Also a separate inner ring can be applied.
Furthermore two separate outer rings 25, 26 are provided, which are
supported with respect to each other in axial direction by means of
a spacer ring 27. Also a one piece outer ring can be applied.
Between the races of the inner ring member 11 and the outer rings
25, 26, two series of balls 28 are accommodated.
[0017] As mentioned, the discs 4, 5 are stably supported with
respect to the housing by means of the hub units 7, 8. Additionally
however, a further support in the form of a hollow central shaft 21
is applied which slideably fits within the bore 29 of each disc 4,
5 and hub unit 7, 8. The hollow central shaft 21 may engage these
elements through an axial key/groove connection or a ball/raceway
connection. Under ideal running conditions (no slip) this hollow
central shaft is not necessary.
[0018] The discs 4, 5 are axially movable with respect to each
other through the screw drive means 6 which comprises a central
screw shaft 16 with opposite screw thread parts 17, 18.
Furthermore, each disc, 5 or hub unit 7, 8 carries a nut 19, 20
which engages one of the screw thread parts 17, 18.
[0019] The central screw shaft 16 is connected to a mechanical
control means which provides a relative rotation between said
central screw shaft 16 and the corresponding pulley set 2, 3.
[0020] The pulley sets 2, 3, in particular the nuts 19, 20 thereof,
are each provided with coupling means 14, 22 for connection to a
drive/driven shaft. This coupling means is constituted by a
telescoping end and has grooves which axially displaceably can
engage a correspondingly shaped end of said drive/driven
shafts.
[0021] The embodiment shown in FIG. 2 is, to a large extent,
similar to the embodiment according to FIG. 2. Corresponding parts
have been identified therein with the same reference numerals.
[0022] The hub units 7, 8 of the continuously variable transmission
according to FIG. 2 each comprise roller bearings 30, the fixed
outer ring 31 of which is connected to the housing 1. The fixed
outer ring 31 has shoulders 32, between which the series of rollers
33 are accommodated with slight axial play.
[0023] The inner ring 34 is clamped on the hub units 7, 8, and
mechanically walk in axial direction with a mechanical means such
as a circlip or by material upsetting using cold forming or orbital
forming. The inner ring 34 can as an alternative also be formed in
one piece with the hub. The raceway of said ring 34 has a width
which is larger than the distance between the shoulders 32 of the
outer rings 31.
[0024] The discs 4, 5, supported by the hub units 7, 8 may now be
moved out of each other and towards each other due to the fact that
the rollers 33 are not only in rolling contact with the inner rings
34, but also in sliding contact. Under running conditions, this
axial sliding movement can take place in a very smooth way.
[0025] Although the hub unit comprises a single row bearing, also
one or more separate bearings may be applied. The bearings may
include ball and roller bearings, e.g. taper roller, needle
bearings or spherical by shaped roller bearings. The belt 24 can be
cooled by lubricant or with a special liquid or with air.
[0026] Furthermore, the pulley hub units and also the continuously
variable transmission as a whole contains sensors for controlling
and monitoring load, number of revolutions, temperature, etc. The
pulley hub units can be self contained, greased and sealed for
life.
[0027] The discs have a V-shaped groove with a minimum width of 15
mm. The enclosed angle of the V-shape varies between 5 to 30
degrees. The surface contacts of the hub and the flexible belt can
be straight, curved or a combination thereof.
[0028] One or both pulley sets can be equipped with springs to
position or preload the flexible drive means. The components of the
pulley hub unit can be made of metallic or non-metallic material,
composite material, powder material, etc. Furthermore, the facing
surfaces of the disc may have a coating to improve the frictional
characteristics for improving torque transfer. The discs may be
cold formed and/or hard turned or whirled for providing optimal
frictional characteristics for torque transfer as well. The discs
can be made of cast iron with a hardened surface, e.g. obtained by
laser cladding to obtain the required wear resistant and frictional
characteristics for torque transfer.
[0029] The inner ring of the pulley hub unit may form a unity with
the nut of screw device. Furthermore, the pulley hub unit may have
a double row angular contact bearing, one raceway of which is
integrated in the hub and the other of which is a separate ring
locked by cold forming or mechanical locking device onto the
hub.
* * * * *